Heat exchanger

ABSTRACT

Heat exchanger or unit for a heat exchanger for heat exchanging media reacting vigorously at direct contact composed of one tube for a heat transferring medium and one or more tubes for a heat absorbing medium each tube for the heat absorbing medium being externally in heat conductive contact for at least a large part of its length with the tube for the heat transferring medium by means of a channel-shaped recess provided externally in the wall of the tube for the heat transferring medium, each recess forming a location for a tube for the heat absorbing medium, the profile of which location corresponds to the external shape of each tube for the heat absorbing medium, and is carried out in such a way that the tube for the heat absorbing medium is located in this recess for not more than half its circumference.

United States Patent [191 De Clercq Mar. 26, 1974 HEAT EXCHANGER Willy J. C. De Clercq, Voorhout, Netherlands [75] Inventor:

[73] Assignee: B. V. Neratoom, The Hague,

Netherlands [22] Filed: Apr. 7, 1969 211 Appl. No.: 813,856

[52] US. Cl. 165/171, 122/510 [51] Int. Cl. F281) l/32 [58] Field of Search..... 165/168, 171.2, 177,181.2,

Primary Examiner-Charles J. Myhre Assistant Examiner-Theophil W. Streule, Jr. Attorney, Agent, or Firm-Hammond & Littell 57 ABSTRACT Heat exchanger or unit for a heat exchanger for heat exchanging media reacting vigorously at direct contact composed of one tube for a heat transferring medium and one or more tubes for a heat absorbing medium each tube for the heat absorbing medium being externally in heat conductive contact for at least a large part of its length with the tube for the heat transferring medium by means of a channel-shaped recess 1 provided externally in the wall of the tube for the heat transferring medium, each recess forming a location for a tube for the heat absorbing medium, the profile of which location corresponds to the external shape of each tube for the heat absorbing medium, and is carried out in such a way that the tube for the heat absorbing medium is located in this recess for not more than half its circumference.

4 Claims, 5 Drawing Figures FATENTED mes m SHEET 1 BF 2 FlG.2

INVENTOR. WILLY J. C. DE CLEROQ BY C v We A k .XAMQ

A T TOR/VEYS INVENTOR. W/LLY J. c. DE CLERCQ HEAT EXCHANGER The invention relates to a heat exchanger or tubeunit for a heat exchangerin particular for applications for heat-exchanging media that react vigorously at direct contact, such as for example in a steam generator operating with liquid sodium and in a heat exchanger in which CO is heated by liquid sodium, this heat exchanger being composed of at least one tube for a heattransferring medium and at least one tube for a heatabsorbing medium, every tube for the heat-absorbing medium along a large part of its length being externally in heat-conductive contact with a tube for the heattransferring medium. With media between which heat transfer takes place in general there is one medium with a relatively low pressure and one medium with a relatively high pressure. It is known from the literature on this subject that for the exchange of heat liquid sodium can be applied as heat-transferring medium to produce steam. Because sodium and water react vigorously at mutual contact the heat exchange between these two media necessitates special safety measures.

To prevent such a sodium-water reaction, with a well-known fast reactor both the water and the sodium are carried through separate tubes, when from a number of these tubes, entirely separated from each other, a heat exchanger is formed with the aid of laminations of heat-conductive material placed against each other, those laminations forming a block in which the tubes are provided, and having mutually externally heatconductive contact.

Such a construction, however, is rather complicated and expensive from a constructional point of view.

Besides, because in this construction the tubes so to speak are embedded in the laminations, in the event of leakage, in one of the tubes, egressing sodium or steam will put the heat exchanger under pressure because these media cannot escape, causing the heat exchanger easily to be damaged or destroyed.

Another drawback of this construction is that in the event of leakage of one or more tubes it is very difficult, if not impossible, to detect this leakage.

Still another drawback of this construction is that in the event of repair or replacement of one of the tubes the entire heat exchanger will have to be dismounted.

It is the primary object of the invention to exclude a reaction between the two media in a heat exchanger in particular sodium and water or sodium and CO and it is another object of the invention to provide a heat exchanger that does not possess the above drawbacks, is simple to construct, in case of leakage the egressing medium being able to escape easily, and further a leakage being easily detectable, and the tubes being simply dismountable and replaceable.

For that purpose the heat exchanger according to the invention is characterized in that every tube for the heat-transferring medium externally is provided with at least one channel-shaped recess, against which lies a tube for the heat-absorbing medium and the profile of which in the location where the tubes are lying against each other corresponds to the external shape of the tube for the heat-absorbing medium.

As a resultof the above arrangement of the individual tubes a heat exchanger is obtained in which on the one hand there is always a double wall between the heat-exchanging media, and in which on the other a directly heat-transferring contact between the tubes is obtained.

According to the invention the channel-shaped recess is carried out in such a way that the tube for the heat-absorbing medium lying in that recess, is taken into it for not more than half its circumference in order to obtain sufficient free surface of tube wall to allow, if necessary, one of the media to escape and to facilitate the leakage detection.

In order to keep the dimensions of the heat exchanger according to the invention as restricted as possible, in the tube for the heat-transferring medium preferably several channel-shaped recesses will be provided.

In this way there will be created between the tubes an intensive heat-transferring contact along a large part of the surfaces of the two wall tubes.

In order to increase the heat transfer in this respect it may be of advantage to apply into the channelshaped recesses at the location where the tube walls of the two media are lying against each other, between these two walls, an adequately heat-conductive lute of a mechanical strength slight in respect of the tube walls. For this purpose a two-component lute could be used composed of graphite for the thermal conductivity and of water glass for rendering mechanical strength.

In the event of leakage in one of the tube walls another tube wall will always remain between the two media to prevent a sodium-water reaction. Moreover, in the heat-exchanger according to the invention the medium egressing as a result of this leakage will be allowed to escape in a simple way. In case such a leakage occurs in the contact surface between the tubes the or one of the tubes may locally be deformed or even may get loose without causing a damage elsewhere in the heat exchanger.

As the tubes as such further are not secluded a leakage, if any, is easy to detect and replacement of the 'tubes is simple. Due to the above safeguarding of the heat exchanger according to the invention radio-active sodium from the primary cooling-circuit of the reactor can also be used as heat-transferring medium with water and steam as heat-absorbing media.

This offers the advantage that an intermediate circuit operating with non-radioactive liquid sodium can be dispensed with.

By preference, in the tubes a heat-exchange according to the counterflow principle will be applied.

Hereinafter the invention will further be elucidated with reference to embodiments of a heat exchanger operating with liquid sodium, given in the drawing:

FIGS. 1, 2 and 3 herewith each give in cross-section embodiments with a central tube for feeding through sodium, the water tubes or steam tubes being distributed evenly over the outer wall of this tube.

FIG. 4 gives a view and FIG. 5 a cross-sectional view of another embodiment, in which a wide tube, rectangular in section, is applied for feeding through sodium, at the broad sides of which tube the water tubes or the steam tubes are transversily provided in the shape of a In FIGS. 1 and 2 the entire tube wall is profiled for shaping these channel-shaped recesses, whereas in FIG. 3 the tube wall is thicker and the channel-shaped recesses are only provided in the outer wall.

The channel-shaped recesses in the sodium tube have such a shape that the water tubes or steam tubes are taken into these recesses for not more than half their circumferences in order to retain both at the sodiumside and the steam side sufficient tube surface to allow sodium or steam to escape and to facilitate leak age detection.

In the embodiments according to FIGS. 1, 2 and 3 the sodium and the steam are fed through the respective tubes in counterflow.

In FIGS. 4 and 5 the sodium tube is a wide flat rectangular tube 1, channel-shaped recesses 2 being provided in the broad walls 4 of the tube in a direction perpendicular to the direction of flow of the sodium through tube 1.

In these channel-shaped recesses 2 the water tubes or steam tubes are provided in the shape of a pipe coil 3.

I claim:

1. A tube assembly for a heat exchanger adapted for media which react violently upon direct contact comprising a large tube provided with at least one external channel-shaped depression therein and at least one smaller tube which for a large part of its length is disposed with at most half of its circumference in the said channel-shaped depression in the large tube whose profile corresponds to the external shape of the smaller tube, the smaller tube being secured in the depression in the larger tube with means resulting in good thermal contact between the corresponding parts of the two tube surfaces and in only a slight strength of the connection as compared with the strength of the tube walls.

2. A tube assembly as claimed in claim 1, wherein the two tubes are secured together solely by an adhesive located between a substantial part of the two corresponding tube surfaces, the said adhesive forming a connection which has good heat conductivity and whose mechanical strength is slight as compared with the strength of the tube material.

3. Heat exchanger according to claim 1, wherein the tube for the heat-transferring medium has several channel-shaped recesses, which are evenly distributed over the circumference.

4. Heat exchanger according to claim 1, wherein every channel-shaped recess is provided in a direction practically parallel to the centre line of the tube.

UNITED- siwrEs PATENT OFFICE CERTIFICATE OF CORRECTION Patent Np. 9 7 Dated March 26 1914 Inventor) J C. De Clercq 7 It is certified that erfbr appears in the above-identified patent and that saidLetters Patent arehereby corrected as shown below:

Column 1 1in 7, in{sert Claims priority application 'Nethr lahdmn N o 6'8 05 s22 filed April 18, 1968 S i g'nsd and sealed this, 24th day of September 1974.

(SEAL) Attest: v McCOY M. .GIBSON JR. I c. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-105O (10-69) USCOMWDC 603mm" 9 U. S GOVERNMENT PRINTING OFFICE 1 I9, 0-356-33h 

1. A tube assembly for a heat exchanger adapted for media which react violently upon direct contact comprising a large tube provided with at least one external channel-shaped depression therein and at least one smaller tube which for a large part of its length is disposed with at most half of its circumference in the said channel-shaped depression in the large tube whose profile corresponds to the external shape of the smaller tube, the smaller tube being secured in the depression in the larger tube with means resulting in good thermal contact between the corresponding parts of the two tube surfaces and in only a slight strength of the connection as compared with the strength of the tube walls.
 2. A tube assembly as claimed in claim 1, wherein the two tubes are secured together solely by an adhesive located between a substantial part of the two corresponding tube surfaces, the said adhesive forming a connection which has good heat conductivity and whose mechanical strength is slight as compared with the strength of the tube material.
 3. Heat exchanger according to claim 1, wherein the tube for the heat-transferring medium has several channel-shaped recesses, which are evenly distributed over the circumference.
 4. Heat exchanger according to claim 1, wherein every channel-shaped recess is provided in a direction practically parallel to the centre line of the tube. 